added new stepper library examples

libraries/Stepper/examples/stepper_speedControl/stepper_speedControl.pde

@@ -0,0 +1,49 @@
+
+/* 
+ Stepper Motor Control - speed control
+ 
+ This program drives a unipolar or bipolar stepper motor. 
+ The motor is attached to digital pins 8 - 11 of the Arduino.
+ A potentiometer is connected to analog input 0.
+ 
+ The motor will rotate in a clockwise direction. The higher the potentiometer value,
+ the faster the motor speed. Because setSpeed() sets the delay between steps, 
+ you may notice the motor is less responsive to changes in the sensor value at
+ low speeds.
+ 
+ Created 30 Nov. 2009
+ Modified 28 Oct 2010
+ by Tom Igoe
+ 
+ */
+
+#include <Stepper.h>
+
+const int stepsPerRevolution = 200;  // change this to fit the number of steps per revolution
+// for your motor
+
+
+// initialize the stepper library on pins 8 through 11:
+Stepper myStepper(stepsPerRevolution, 8,9,10,11);            
+
+int stepCount = 0;         // number of steps the motor has taken
+
+void setup() {
+  // initialize the serial port:
+  Serial.begin(9600);
+}
+
+void loop() {
+  // read the sensor value:
+  int sensorReading = analogRead(A0);
+  // map it to a range from 0 to 100:
+  int motorSpeed = map(sensorReading, 0, 1023, 0, 100);
+  // set the motor speed:
+  if (motorSpeed > 0) {
+    myStepper.setSpeed(motorSpeed);
+    // step 1/100 of a revolution:
+    myStepper.step(stepsPerRevolution/100);
+  } 
+}
+
+